Various types of housings have been used for electronics intended to be placed beneath the skin of a person such as the radio frequency receiver included in a cochlear implant of the type described in U.S. Pat. No. 4,352,960 incorporated herein by reference.
One such housing has been of titanium which interferes with transmission of high frequency signals.
Epoxy encapsulant has been used for housing the receiving coil and electronics, but because it does not provide a hermetic seal, eventually body fluids will attack and degrade the electronics.